1. Field of the Invention
The present invention relates generally to mobile communication systems, and more specifically to a location system for providing information services to clients as to the location of user equipment (UE) terminals.
2. Description of the Related Art
As a value-added feature of mobile communication service, location information service is an important subject currently being under study by the Third Generation Partnership Program (3GPP) to enhance the functionality of mobile terminals. The 3GPP Technical Specification 23.271 v.5.1.0, “Functional stage 2 description of LCS”, December 2001 (hereinafter Document 1), is a current standard that specifies particulars of location information services. Since information as to the location of a mobile terminal is very sensitive to the user and must be protected, mobile communication networks are provided with sophisticated privacy protection functionality which imposes restriction control on accesses according to end-user's privacy settings.
The privacy settings as requested by mobile users are of two types. One is a type of information which can be determined at the time a location request is sent to the location system, such as the name of clients or service classes. The other is of a type of information which can be determined only at the time after the location information of the target mobile terminal is obtained, such as the geographic location of a target user equipment or the time of day the location information is obtained from the location system.
The 3GPP location information system, as described in Document 1 and shown in FIG. 12, is made up of client terminal 101, GMLC (Gateway Mobile Location Center) 102, SGSN/MSC (Serving General packet radio service Support Node/Mobile Services switching Center) 103, local wireless network known as RAN (Radio Access Network) 104 and UE (User Equipment) terminal 105 connected to the RAN via wireless link. HLR/HSS (Home Location Register/Home Subscriber Server) 106 is connected to the GMLC 102 as a database for holding the identity of the RAN to which UE terminals are connected.
When a location request is sent to the system for a target UE terminal, the SGSN/MSC 103 that manages the RAN to which the UE terminal is connected takes the responsibility for protecting the privacy of the terminal. Client terminals which are authorized to access a UE terminal are registered in the location system in advance by the user of the UE terminal in order to protect the user from unauthorized accesses.
However, a need has recently arisen to provide versatile protection functionality, the current client-based scheme is not sufficient to fulfil the need. To implement a versatile protection mechanism for a given service area of the current 3GPP system, it would be necessary to extend the privacy check functionality of all SGSN/MSC systems that exist in that service area. However, the introduction of such a versatile protection mechanism in the SGSN/MSC systems would be too costly if future expansion and system growth are to be taken into account. It is desired that a versatile privacy check mechanism should be provided in a system other than SGSN/MSC. Additionally, a desirable feature of the versatile protection mechanism is to protect UE terminals roaming in an external network from unauthorized access from client terminals of the external network.
With the background just described, an enhanced privacy check mechanism has been proposed in Chapter 7 of 3GPP Technical Report 23.871 v1.1.0, “Enhanced support for User Privacy in location services”, tdoc S2-020316, Jan. 23, 2002 (hereinafter Document 2).
However, privacy items protected by the enhanced mechanism relate only to those associated with the time at which location request is made and sent to the location service system. No consideration is taken of those privacy items which can be determined only at the time after the location information of the target mobile terminal is obtained. Furthermore, while Document 2 proposes a scheme for serving requests from clients of a remote network to UE terminals of a home network through collaborations between the networks, specific functions and responsibilities are yet to be determined.